Wine Yeasts, Small but Perfectly Formed.
For those of you who follow our podcast, I heard it through the grapevine: you’ll know that this week in our W’alphabet was S. S for many wine related terms, such as Sangiovese, Sauvignon Blanc, Savennieres, but also Saccharomyces Cerevisiae, hence the re-posting of this 2018 blog by Harriet from the Tindal site. If you’re confused about the difference between natural and wild yeasts, this should help…..
Meet Saccharomyces Cerevisiae, an unassuming single celled fungi with the capability to change the sugar and water in grapes into wine! I can see you’re warming to this little microscopic cell already.
So Saccharomyces Cerevisiae, SC for short has 16 other genera within the yeast species that can also turn water into wine. They share the same propensity for complicated names, but none share the stamina and success of SC. SC is always the last to leave the party, fermenting till dawn, enjoying the added pressure of increasing alcohol, lapping up the extra heat, while others such as Hanseniaspora, Pichia and Torulaspora fade away into the depths of the fermenting wine.
wild ferments and natural wines have ostracised SC in some more ‘funky’ circles. Let’s stop that right now! SC is in every ferment, wild or cultured. SC has been shown to breed in the wild, adapting specifics to the vineyard location with different strains being discovered in wineries globally. SC mutates, adapts and alters to suit surroundings whilst still offering the strongest fermentation capabilities.
A study from 1966 on yeast showed that during a wild ferment Kloeckera apiculata and Hanseniaspora uvarum peak early. SC on the other hand shows some self discipline and paces itself throughout the process, the sole surfer left on the wave of the final ferment. At Kumeu River winery in New Zealand, they found that SC was highly diverse with up to 12 strains detected in a single ferment. They believe that SC is inter-breeding and these off-spring are adding complexities to an efficient and most importantly finished ferment. Rubbishing claims that SC is cultured, one dimensional and indistinct.
Bo Barrett, original hipster and owner of the famed Chateau Montelena in Napa Valley believes that if there’s a winery up the road using commercial yeast, strains are going to find their way to your ferment over time. Kym Teusner in the Barossa, agrees. You can’t have a completely natural ferment when there are commercial strains roaming the airways.
But there is some substance to the interest in these wild, weaker species. Recent work has been looking at substantiating claims that Kloekera can increase mouthfeel on a finished wine. Brettanomyces (the bad boy) gives a sense of sweaty horse to a wine, something surprisingly accepted by a large band of wine drinkers. Bayanus yeasts have been shown to enhance that
Yeasts don’t just ferment, they can influence the aromatics of wine, beneficially or not so beneficially. Colour is also in their CV with a canny ability to stabilise colour in collaboration with Sulphur Dioxide. Jules Chauvet, known as the ‘father of natural wine’ trialled expressions from yeasts. He sterilised musts and seeded with different yeast varieties. A panel of tasters tried the wines; indigenous yeast came out on top as the most appreciated flavour.
But, I leave you with this. If the yeasts are affecting the overall taste of the wine, is that wine a product of the vineyard from where it originated or the distribution of yeasts, on that particular day in that particular winery. Or, are we looking at the complex tapestry of factors that culminate in an almost mythical way to produce a wine that with each batch, each site, each vintage is different. These are the wines that take souls, these wines are those made in the vineyard with integrity and passion, this is why we love wine.
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